Field evaluation of validity and feasibility of Pan-Lassa rapid diagnostic test for Lassa fever in Abakaliki, Nigeria: a prospective diagnostic accuracy study.

BACKGROUND: Lassa fever is a viral haemorrhagic fever with few options for diagnosis and treatment; it is also under-researched with knowledge gaps on its epidemiology. A point-of-care bedside test diagnosing Lassa fever, adhering to REASSURED criteria, is not currently available but is urgently needed in west African regions with high Lassa fever burden. We aimed to assess the validity and feasibility of a rapid diagnostic test (RDT) to confirm Lassa fever in people in Nigeria. METHODS: We estimated the diagnostic performance of the ReLASV Pan-Lassa RDT (Zalgen Labs, Frederick, MD, USA) as a research-use-only test, compared to RT-PCR as a reference standard, in 217 participants at a federal tertiary hospital in Abakaliki, Nigeria. We recruited participants between Feb 17, 2022, and April 17, 2023. The RDT was performed using capillary blood at the patient bedside and using plasma at the laboratory. The performance of the test, based on REASSURED criteria, was assessed for user friendliness, rapidity and robustness, sensitivity, and specificity. FINDINGS: Participants were aged between 0 and 85 years, with a median age of 33·0 years (IQR 22·0-44·3), and 24 participants were younger than 18 years. 107 (50%) participants were women and 109 (50%) were men; one participant had missing sex data. Although the specificity of the Pan-Lassa RDT was high (>90%), sensitivity at bedside using capillary blood was estimated as 4% (95% CI 1-14) at 15 min and 10% (3-22) at 25 min, far below the target of 90%. The laboratory-based RDT using plasma showed better sensitivity (46% [32-61] at 15 min and 50% [36-64] at 25 min) but did not reach the target sensitivity. Among the 52 PCR-positive participants with Lassa fever, positive RDT results were associated with lower cycle threshold values (glycoprotein precursor [GPC] gene mean 30·3 [SD 4·3], Large [L] gene mean 32·3 [3·7] vs GPC gene mean 24·5 [3·9], L gene mean 28·0 [3·6]). Personnel conducting the bedside test procedure reported being hindered by the inconvenient use of full personal protective equipment and long waiting procedures before a result could be read. INTERPRETATION: The Pan-Lassa RDT is not currently recommended as a diagnostic or screening tool for suspected Lassa fever cases. Marked improvement in sensitivity and user friendliness is needed for the RDT to be adopted clinically. There remains an urgent need for better Lassa fever diagnostics to promote safety of in-hospital care and better disease outcomes in low-resource settings. FUNDING: Médecins Sans Frontières.

Better care for babies: the added value of a modified reverse syphilis testing algorithm for the treatment of congenital syphilis in a maternity Hospital in Central African Republic.

BACKGROUND: In high syphilis prevalence settings, the syphilis testing and treatment strategy for mothers and newborns must be tailored to balance the risk of over treatment against the risk of missing infants at high-risk for congenital syphilis. Adding a non-treponemal test (Rapid Plasma Reagin - RPR) to a routine rapid treponemal test (SD Bioline Syphilis 3.0) for women giving birth can help distinguish between neonates at high and low-risk for congenital syphilis to tailor their treatment. Treatment for neonates born to RPR-reactive mothers (high-risk) is 10 days of intravenous penicillin, while one dose of intramuscular penicillin is sufficient for those born to RPR non-reactive mothers (low-risk). This strategy was adopted in March 2017 in a Médecins Sans Frontières supported hospital in Bangui, Central African Republic. This study examined the operational consequences of this algorithm on the treatment of newborns. METHODS: The study was a retrospective cohort study. Routine programmatic data were analysed. Descriptive statistical analysis was done. Total antibiotic days, hospitalization days and estimated costs were compared to scenarios without RPR testing and another where syphilis treatment was the sole reason for hospitalization. RESULTS: Of 202 babies born to SD Bioline positive mothers 89 (44%) and 111(55%) were RPR-reactive and non-reactive respectively (2 were unrecorded) of whom 80% and 88% of the neonates received appropriate antibiotic treatment respectively. Neonates born to RPR non-reactive mothers were 80% less likely to have sepsis [Relative risk (RR) = 0.20; 95% Confidence interval (CI) = 0.04-0.92] and 9% more likely to be discharged [RR = 1.09; 95% CI = 1.00-1.18] compared to those of RPR-reactive mothers. There was a 52%, and 49% reduction in antibiotic and hospitalization days respectively compared to a scenario with SD-Bioline testing only. Total hospitalization costs were also 52% lower compared to a scenario without RPR testing. CONCLUSIONS: This testing strategy can help identify infants at high and low risk for congenital syphilis and treat them accordingly at substantial cost savings. It is especially appropriate for settings with high syphilis endemicity, limited resources and overcrowded maternities. The babies additionally benefit from lower risks of exposure to unnecessary antibiotics and nosocomial infections.

Ensuring On-site Ebola Patient Monitoring and Follow-up: Development of a Laboratory Structure Embedded in an Ebola Treatment Center.

The capacity to rapidly distinguish Ebola virus disease from other infectious diseases and to monitor biochemistry and viremia levels is crucial to the clinical management of suspected Ebola virus disease cases. This article describes the design and practical considerations of a laboratory straddling the high- and low-risk zones of an Ebola treatment center to produce timely diagnostic and clinical results for informed case management of Ebola virus disease in real-life conditions. This innovation may be of relevance for actors requiring flexible laboratory implementation in contexts of high-communicability, high-lethality disease outbreaks.

Diagnosis and management of Ebola samples in the laboratory.

The magnitude of the 2014-2016 West African Ebola virus outbreak has highlighted the importance of immediate and rapid deployment of control measures in affected areas. While many prophylactic and therapeutic options entered clinical trials in the past two years, larger use to impact on Ebola spread will not be possible until at least one product meets final approval by regulatory agencies. Control of the West African outbreak was achieved almost entirely by breaking chain of transmissions through case identification and specialized treatment, communication, safe burials and other proven methods. To achieve this in a timely manner, epidemiologists and medical teams are working in concert with laboratories to identify infected individuals and provide care within Ebola treatment units. Herein, we review an outbreak response workflow from the point of view of mobile laboratories and summarize methods that have been used by them during the West African Ebola virus outbreak of 2014-2016.

Feasibility of Xpert Ebola Assay in Médecins Sans Frontières Ebola Program, Guinea.

Rapid diagnostic methods are essential in control of Ebola outbreaks and lead to timely isolation of cases and improved epidemiologic surveillance. Diagnosis during Ebola outbreaks in West Africa has relied on PCR performed in laboratories outside this region. Because time between sampling and PCR results can be considerable, we assessed the feasibility and added value of using the Xpert Ebola Assay in an Ebola control program in Guinea. A total of 218 samples were collected during diagnosis, treatment, and convalescence of patients. Median time for obtaining results was reduced from 334 min to 165 min. Twenty-six samples were positive for Ebola virus. Xpert cycle thresholds were consistently lower, and 8 (31%) samples were negative by routine PCR. Several logistic and safety issues were identified. We suggest that implementation of the Xpert Ebola Assay under programmatic conditions is feasible and represents a major advance in diagnosis of Ebola virus disease without apparent loss of assay sensitivity.

Errors generated by a point-of-care CD4+ T-lymphocyte analyser: a retrospective observational study in nine countries.

OBJECTIVE: To estimate the proportion of invalid results generated by a CD4+ T-lymphocyte analyser used by Médecins Sans Frontières (MSF) in field projects and identify factors associated with invalid results. METHODS: We collated 25,616 CD4+ T-lymphocyte test results from 39 sites in nine countries for the years 2011 to 2013. Information about the setting, user, training, sampling technique and device repair history were obtained by questionnaire. The analyser performs a series of checks to ensure that all steps of the analysis are completed successfully; if not, an invalid result is reported. We calculated the proportion of invalid results by device and by operator. Regression analyses were used to investigate factors associated with invalid results. FINDINGS: There were 3354 invalid test results (13.1%) across 39 sites, for 58 Alere PimaTM devices and 180 operators. The median proportion of errors per device and operator was 12.7% (interquartile range, IQR: 10.3-19.9) and 12.1% (IQR: 7.1-19.2), respectively. The proportion of invalid results varied widely by country, setting, user and device. Errors were not associated with settings, user experience or the number of users per device. Tests performed on capillary blood samples were significantly less likely to generate errors compared to venous whole blood. CONCLUSION: The Alere Pima CD4+ analyser generated a high proportion of invalid test results, across different countries, settings and users. Most error codes could be attributed to the operator, but the exact causes proved difficult to identify. Invalid results need to be factored into the implementation and operational costs of routine CD4+ T-lymphocyte testing.

Prospective evaluation of diagnostic accuracy of dried blood spots from finger prick samples for determination of HIV-1 load with the NucliSENS Easy-Q HIV-1 version 2.0 assay in Malawi.

HIV-1 viral load (VL) testing is not widely available in resource-limited settings. The use of finger prick dried blood spot (FP-DBS) samples could remove barriers related to sample collection and transport. Measurement of VL using DBS from EDTA venous blood (VB-DBS) in place of plasma has previously been validated using the NucliSENS Easy-Q HIV-1 v2.0 assay, but information on the accuracy of FP-DBS samples for measuring VL is limited. This prospective study, conducted at Thyolo District Hospital in southern Malawi, compared VL levels measured on FP-DBS samples and plasma using the NucliSENS Easy-Q HIV-1 v2.0 assay. Comparability was assessed by means of agreement and correlation (131 patients with VLs of ≥100 copies/ml), sensitivity, and specificity (612 patients on antiretroviral treatment [ART]). Samples of EDTA venous blood and FP-DBS from 1,009 HIV-infected individuals were collected and prepared in the laboratory. Bland-Altman analysis found good agreement between plasma and FP-DBS VL levels, with a mean difference of -0.35 log10, and 95% limits of agreement from -1.26 to 0.55 log10. FP-DBS had a sensitivity of 88.7% (95% confidence interval [CI], 81.1 to 94.4%) and a specificity of 97.8% (95% CI, 96.1 to 98.9%) using a 1,000-copies/ml cut point and a sensitivity of 83.0% (95% CI, 73.4 to 90.1%) and a specificity of 100% (95% CI, 99.3 to 100%) using a 5,000-copies/ml cut point. This study shows that FP-DBS is an acceptable alternative to plasma for measuring VL using the NucliSENS Easy-Q HIV-1 v2.0. We are conducting a second study to assess the proficiency of health workers at preparing FP-DBS in primary health care clinics.

Evaluation of four rapid tests for diagnosis and differentiation of HIV-1 and HIV-2 infections in Guinea-Conakry, West Africa.

With both HIV-1 and HV-2 prevalent in Guinea-Conakry, accurate diagnosis and differentiation is crucial for treatment purposes. Thus, four rapid HIV tests were evaluated for their HIV-1 and HIV-2 diagnostic and discriminative capacity for use in Guinea-Conakry. These included SD Bioline HIV 1/2 3.0 (Standard Diagnostics Inc.), Genie II HIV1/HIV2 (Bio-Rad), First Response HIV Card Test 1-2.0 (PMC Medical) and Immunoflow HIV1-HIV2 (Core Diagnostics). Results were compared with gold standard tests (INNO-LIA HIV-I/II Score) and NEW LAV BLOT II (Bio-Rad). Four hundred and forty three sequential stored HIV-positive serum samples, of known HIV-type, were evaluated. Genie II HIV1/HIV2, Immunoflow HIV1-HIV2 and SD Bioline HIV 1/2 3.0 had 100% sensitivity (95% CI, 98.9-100%) while for First Response HIV Card Test 1-2.0 this was 99.5% (95% CI, 98.2%-99.9%). In terms of discriminatory capacity, Genie II HIV1/HIV2 identified 382/ 384(99.5%) HIV-1 samples, 49/ 52(95%) HIV-2 and 7/7(100%) HIV-positive untypable samples. Immunoflow HIV1-HIV2 identified 99% HIV-1, 67% HIV-2 and all HIV-positive untypable samples. First Response HIV Card Test 1-2.0 identified 94% HIV-1, 64% HIV-2 and 57% HIV-positive untypable samples. SD-Bioline HIV 1/2 3.0 was the worst overall performer identifying 65% HIV-1, 69% HIV-2 and all HIV-positive untypable samples. The use of SD Bioline HIV 1/2 3.0 (the current standard in Guinea-Conakry) as a discriminatory HIV test is poor and may be best replaced by Immunoflow HIV1-HIV2.